How to calculate heat load (a 5-step tutorial).

Calculating a heat load is necessary before the installation of a radiant heating system can begin, since different types of radiant heating systems have different BTU output values.

A typical heat load calculation consists of surface heat loss calculation and heat loss due to air infiltration. Both should be done separately for every room in the house, so having a floor plan with dimensions of all walls, floors, ceiling, as well as doors and windows is a good place to start.

Below is a sample 6-step manual to surface heat loss calculation:

Step 1 – Calculate Delta T (Design Temperature):

Delta T is a difference between indoor design temperature (T1) and outdoor design temperature (T2), where indoor design temperature is typically 68-72F depending on your preference, and outdoor design temperature is a typical low during the heating season. The former can be obtained by calling your local utility company.